<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8" />
		<title>1物理像素边框</title>
		<meta name="viewport" content="width=device-width,initial-scale=1,viewport-fit=cover"/>
		<style>
			#demo{
				width: 200px;
				height: 100px;
				margin: 0 auto;
				border: 1px solid black;
				background-color:#ddd;
			}
			@media screen and (-webkit-min-device-pixel-ratio:2){
				#demo{
					border: 0.5px solid black;
				}
			}
			@media screen and (-webkit-min-device-pixel-ratio:3){
				#demo{
					border: 0.333px solid black;
				}	
			}
		</style>
	</head>
	<body>
		<div id="demo"></div>
	</body>
</html>